The present invention relates to an automatic examination system for motor vehicles which can quickly and automatically examine whether an engine of an automobile or the like is good or bad without making contact with the body of the automobile or the like.
Heretofore, in the known examination system for an engine of an automobile, various sensors were mounted at the respective portions of the engine to pick up electrical, magnetic, optical, pneumatic or other variations in the form of signals; meters or indicators were actuated by processing the signals, and the states of the respective portions were thereby measured and examined. Accordingly, such known systems were inadequate for momentary measurement and momentary examination because it was necessary to stop an automobile to be examined and to mount senors thereon.
More particularly, it was impossible to measure and examine a state of an engine of an automobile stopping by a gas station or the like for the purpose of receiving fuel, during the short time needed for receiving fuel while a hood is kept closed without previously mounting sensors to the automobile.
The present inventors have conducted research over many years in order to overcome the above-mentioned shortcoming in the prior art, and as a result, when they examined many (about 500) automobiles which were being used by means of a general examination system and statistically analyzed the results of their examination, especially marking the items relating to "uneven rotation" among the various items examined during idling of an engine, they discovered the fact that in the case where uneven rotation exceeding, for example, 50 rpm was produced, the engine was being influenced by other faulty functions such as faulty contact points, a faulty ignition voltage, an insufficient accerelation and output, a faulty battery, faulty tuning of a carburetor, etc. Hence, the present invention was conceived in view of the determination that the condition of an engine can be known simply by merely detecting uneven rotation of the engine on the basis of the above-mentioned knowledge, and that uneven rotation of an engine can be measure regardless of its type, number of cycles, number of cylinders, etc. by measuring the respective period differences of electrical signals such as an ignition noise or sonic signals generated from the engine, that is, through an angular-velocity-like detection method.